Abstract:

Many regions in North America are experiencing water shortages, and these conditions are expected to worsen. The next generation of irrigation scheduling applications must therefore be capable of providing operational advice in support of deficit irrigation strategies. However, the theoretical, technical, and practical challenges associated with deficit irrigation scheduling are far more complex than conventional (full) irrigation.
This dissertation presents three distinct systems for addressing the analytical challenges of deficit irrigation management. The first section of the dissertation presents a simulation framework for agro-ecological simulation. The objective was to develop a method to enable the assembly of simulation models from previously and independently developed component models. Based on a requirements analysis of existing simulation models we developed the ModCom simulation framework. ModCom provides a set of interface specifications that describe components in a simulation. ModCom also provides implementations of the core simulation services. The framework interfaces use well-defined binary standards and allows developers to implement the interfaces using a broad range of computer languages. The Second section describes the Irrigation Efficiency Model (IEM). IEM explicitly analyzes irrigation efficiency, accounts for spatial variability of soil properties and irrigation uniformity, performs simultaneous scheduling for all fields in the farm, accounts for energy use and its associated costs, and uses both ET and soil moisture measurements to enhance the accuracy of the irrigation schedules. IEM was developed specifically for implementing Deficit Irrigation and therefore includes analyses that go beyond the requirements of conventional irrigation scheduling. The third section describes Irrigation Management Online (IMO), a web application for optimum irrigation management. This system uses IEM to generate and deliver irrigation scheduling recommendations. IMO has been developed specifically to support irrigation management when either water supplies or delivery system capacities are limited. To mitigate the complexities of irrigation constraints the system has been designed so that the irrigation manager is an integral part of the irrigation optimization procedure. The final section outlines some of the key challenges that the next generation of schedulers must overcome in order to meet the needs of agricultural irrigation in an increasingly water short future. In addition, this section will discuss how irrigation advisory programs will need to operate differently in terms of what they do and how they do it.